Spatial filtering is one of the main assets of optics for information processing. In this paper we review spatial filtering methods for performing binary logic operations. Many pairs of bits can be processed simultaneously. The input data are arranged in matrix form. The type of operation is usually homogeneous across the matrix. The input is characterized as a diffracting, as a scattering, or as a birefringent structure. Experimental results are shown. Applications of the described method for an optical adder are presented.